Tacchella



Feb. 21, 1956 A. TACCHELLA 2,735,414-

COMBUSTION ENGINES LIQUID COOLING SYSTEM FOR INTERNAL- Filed Dec.

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United States Patent LIQUID COOLING SYSTEM FOR INTERNAL- COMBUSTION ENGINES Adolph Tacchella, Altadena, Calif. Application December 9, 1950, Serial No. 200,022 12 Claims. (Cl. 12341.23)

The present invention relates generally to a liquid coolling system for an internal combustion engine, and more particularly to means for separating the vapor and liquid phases of the coolant in a system of this kind. In its broader aspect, my invention may be used in various cooling systems or with different liquids; but I show and describe it as applied to a particular cooling system of an engine using water.

The advantages of operating an internal combustion engine at a relatively high temperature are widely recognized and need not be detailed here; but in general more favorable operating conditions are had and greater eificiency results from the higher operating temperature. For example, if an engine can be operated with its cooling system in the neighborhood of 210 to 225 F. the engine is operating under better technical conditions than if the cooling system is reduced to temperatures in the range of 160 to 180 F. Yet it is within this latter range that most internal combustion engines normally operate, especially automobile engines. The lower range in these cases is necessary in order to provide reserve cooling capacity in the event of a sustained increase in load or an increase in the temperature of the surrounding air used for cooling the liquid in the engine system. An incidental but important advantage of a high temperature cooling system is the fact that a smaller radiator can be used because there exists at all times a greater temperaure differential between the coolant and the atmosphere.

Liquid cooling systems almost universally ,use a pump to force the coolant through the system at a suitable velocity. In a high temperature cooling system using water, the water is very close to the boiling point when it leaves the cylinder head. The pressure in the cooling system usually drops after the water leaves the cylinder head and this is particularly true at the intake port of the pump. When such a pressure drop occurs, even though no further heat is added to the water, steam forms because the pressure within the system is less than the vapor pressure of the steam at the existing temperature. The result is a condition often referred to as vapor lock in which liquid coolant fails more or less completely to reach the pump and the impeller turns in a pocket of steam with the result that the cooling system circulation drops below an adequate value.

In a stationary installation, the usual way of overcoming this condition is the provision of an elevated reservoir which is sufficiently high above the pump that the resultant gravity head keeps an adequate pressure on the pump intake port to prevent the formation of steam at this point. The use of an elevated reservoir is objectionable in many cases even with stationary installations, and it is obviously impractical to provide such atank for an automobile engine since the minimum head recommended in the standards of the Hydraulic Institute is 17 feet for a water temperature of 215 -F.

Hence it becomes a general object of .my invention to provide an eflicient liquid cooling system for an internal combustion engine adapted to operate with the coolant maintained at a relatively higher temperature.

It isalso an object of my invention to provide a liquid cooling system for an internal combustion engine operating at or near the boiling point of the coolant so that the vapor phase is formed in the system.

A further object of the invention is to provide an efiicient separator of the liquid and vapor phases adapted to use in a cooling system of the character described.

Another object of the invention is to provide a liquid cooling system for an engine which does not require an elevated tank or the like but which utilizes energy from Within the system to feed coolant to the pump intake at an adequate rate at all times.

Still another object of my invention is the provision of a simple cooling system of the character described in which advantage can be taken of the high operating temperature to reduce the size of the radiator and thus produce a cheaper and more economical cooling system.

The above objects of my invention are attained by providing a novel type of vapor phase separator in a novel engine cooling system. The separator has a tank in which a body of the liquid coolant is maintained, the liquid level being below the top of the tank to leave a space above the liquid which is normally filled with vapor. An inlet to the tank is provided below the liquid level. The inlet is formed by passage means providing a passage of which the cross section initially decreases in the direction of flow and then abruptly increases by a substantial amount in order to produce a zone of sharply reduced pressure. The passage forming means of the inlet then continues on, preferably with gradually increasing cross section to accommodate the increased volume of the fluid stream, the increase being caused by vapor formed from liquidas a consequence of the pressure reduction.

The fluid stream is discharged into a separating chamber opening into the tank interior. The vapor phase leaves the liquid phase in this separating chamber and passes into the tank while the liquid phase continues on through the separating chamber and enters an outlet passage which discharges the liquid from the tank. The liquid leaves the tank travelling at an increased velocity because of the expansion of the fluid stream resulting from the formation of the vapor phase and this velocity is utilized to feed the liquid to the pump. The vapor phase is drawn off from the tank at a point above the liquid level.

The outlet from the separator is connected to the pump intake, the connection preferably beingas short as possible in order to minimize friction losses in this connection. -The comparatively high velocity of the liquid leaving the separator carries it into the pump, even though the temperature and pressure conditions are such that vapor might normally be formed at the pump inlet. Actually, the formation of a substantial amount of vapor in the separator reduces the total heat content of the coolant by the time it reaches the pump to such a level that little or no vapor is formed at the pump inlet. As a consequence the pump receives liquid continuously and operates efiiciently at all times. In a system of this character, the vapor drawn off from the separator is conducted to a-radiator or heat exchange unit of any conventional design where thevapor is condensed to liquid and the condensate is returned tothe system.

In this Way the liquid within the cooling system can be maintained within a comparatively narrow temperature range at all points throughout the system though the total heat content changes considerably from one point to another. This condition is possible because of therelati vely great value of the latent heat of vaporization of water. Heat is given up by-the engine to the circulating liquid and then this heat is extracted from the main body of liquid by converting only a portion of the liquid to vapor, the heat energy in the entire body of liquid being utilized to supply the latent heat necessary for vaporization of part of the liquid. This heat is then extracted from the system in the radiator where the vapor is returned to liquid form, normally at a temperature substantially below the boiling point.

How the above objects and advantages of my invention, as well as others not specifically mentioned, are attained will be more readily understood by reference to the following description and to the annexed drawings, in which:

Fig. 1 is a diagrammatic view of an internal combustion engine showing the application theretoof a liquid cooling system embodying the novel features of my invention, including a vapor phase separator of novel design;

Fig. 2 is a longitudinal vertical median section through a vapor phase separator constructed according to my invention',

Fig. 3 is a vertical transverse section on line 3-3 of Fig. 2; and

Fig. 4 is a plan View of the separator with the cover plate removed.

In the drawings I show a novel form of vapor phase separator incorporated in an engine cooling system, and it will be understood that in its broader aspects my invention is not necessarily limited to this particular system. Since water is a commonly and widely used cooling medium in internal combustion engines, I refer herein to theliquid and vapor phases as water and steam respectively but it will also be understood that the invention is not necessarily limited thereto and may be used with liquids other than water.

In Fig. 1, the vapor phase separator generally indicated at is shown as being installed in the liquid cooling system of an internal combustion engine 12 which may be of any type. Engine block 12 has inlet and outlet connections of any conventional type for the coolant circulated through the block. The engine may be either part of a stationary installation or mounted in a vehicle and so rendered mobile.

The separator comprises a tank 14, here shown as being rectangular in cross-section, although other shapes and sizes of tanks may be used. Tank 14 is provided with a removable top cover 15 permitting access to the interior of the separator for assembly and normal service and maintenance operations. The tank illustrated in the drawings is provided with sight glasses 16 in opposite side walls to permit visual inspection of the action inside the tank. This feature is obviously desirable under some circumstances but may be omitted.

Tubular inlet means is provided in one side wall of the tank. This inlet means consists of an initial tubular section 18 slidably mounted in a flanged collar 19 removably attached to the tank wall and a second tubular section 21 continuing on from the first. Section 18 has an internal passageway 20 of circular cross-section which gradually decreases in cross-sectional area inwardly of the tank, that is in the direction of fluid flow. The inner end of passage 20 may have a short section 20a of uniform cross-sectional area as shown, although this is optional and may be omitted. Attached to and carried by inlet tube 18 is a second tubular section 21 having an internal passageway 22 of which the cross-section preferably increases gradually in the direction of fluid flow. This section of the inlet passageway may be of uniform cross-section through out its length if desired, but it is preferable that the crosssection increase gradually as shown.

As shown particularly in Fig. 2, the minimum crosssection of passageway 22 istsubstantially larger than the minimum of passageway 20 and the change from one to the other takes place abruptly so that as the fluid stream moves from passage 20 into passage 22 the cross-section of the fluid stream is suddenly increased with a consequent sudden decrease in the pressure on the fluid. The abrupt character of the increase in cross-sectional area is obtained by making a sharp shoulder at the end of passageway 20 so that the inner end of tube 18 acts as a nozzle projecting a stream of water into passageway 22 within the second tube section 21. The ratio of the minimum areas of the two passageways 22 and 20 is preferably 2:1 or greater in order to secure a satisfactory quantitative change in pressure.

structurally, the two inlet sections may be made as an integral unit although I have here shown tube sections 18 and 21 as being separable and held together by set screw 23. The inlet to the tank is located a short distance above the bottom of the tank and below the water level normally maintained in the tank. The water level normally fluctuates over a moderate range but is ordinarily in the vicinity of the position shown.

A steam separating chamber 25 is formed by tubular member 24 located in the tank at a position below the water level. The chamber receives water and steam discharged from the end of inlet 22. Separating chamber 25 is preferably also of circular cross-section and located in prolongation of inlet passageways 20 and 22. Separating chamber 25 is provided with a steam port 26 in its upper side. The exact shape and size of this port may be varied to suit operating conditions but is here shown as consisting of a longitudinally extending slot with a plurality of short transverse slots 26a. from water within the separating chamber escapes through port 26 into the space in tank 14 above the water level.

Wall means are mounted upon steam chamber tube 24 to form a rectangular well 28 surrounding steam port 26. The side walls of well 28 provide a baffle or shield which extends to a point above the normal water level and thus prevents the main body of water in the tank from flowing into separating chamber 25 through port 26. This action facilitates the upward movement of the steam through the port and into the space above the water level in the tank.

Well 28 consists of a pair of transverse end plates 29 attached to tube 24 one near each end of the separating chamber by bolts 30. End plates 29 are vertically grooved to receive. and hold upright a pair of spaced glass plates 31 that extend between end plates 29 and rest upon angle brackets 32, as shown in Fig. 3. Walls 31 are made transparent when sight glasses 16 are used but may be made of metal when sight glasses 16 are omitted.

Inside of separating chamber 25 is ring 34 which fills a portion of the annular space between the inside surface of tube 24 and the outside of inlet tube 21. Ring 34 preferably fills somewhat more than half of this annular space, leaving an arcuate opening 35 at the bottom of the separating chamber affording communication between the body of water outside tube 24 and the separating chamber inside. In the normal action of the separator described later, water flows into the separating chamber through this Openmg. a

Other tubular means provide a water outlet from .the tank in a wall opposite to the inlet means. For this purpose, outlet tube 40 is slidably mounted in flanged collar 41 attached to a side wall of tank 14. Packing of a suitable type between tube 40 and collar 41 may be furnished if desired, though none is shown. Tube 40 hasan internal passage 42 which, like the other fluid passages mentioned, is preferably circular in cross-section. Passageway 42 has a relatively large diameter at the point of opening into separating chamber 25 from which it receives water. From this relatively large diameter it tapers gradually down to a smaller diameter generally comparable to. the maximum diameter of inlet passageway 20. This decrease in cross-sectional area of passageway 42 in the direction of fluid flow permits the passageway to act as a collector for receiving liquid from the separating chamber which-thenreduees the cross-sectional area of the liquid stream in order to increase its velocity. The annular space between the outside of tube '41} and the inside wall of tube 24 is normally partly filled'byrihg Steam separated- 44. The ring preferably does not occupy a full circle and therefore leaves an opening 45 at the top of the separating chamber communicating with the interior of tank 14. This opening permits the escape of any steam at the last moment before the water enters passageway 42. Obviously, opening 42 may be omitted or changed in size or location. Separating chamber'25 is supported on the two tubular sections 21 and 40 by means of rings 34 and 44. Set screw 46 is provided to hold the separating chamber against longitudinal or rotational movement relative to the other parts. This construction keeps the inlet passage, the separating chamber, and the outlet passage in proper alignment, these threebeing preferably co-axial, in order to provide a straight linear path through the separator.

At the bottom, tank 14 is provided with a pair of threaded bores 43. To one of these is connected pipe 49 which returns condensate to the separator, as will be more fully described, while the other is closed by plug 50. The plug may be removed to drain or refill the tank. By making the two bores 48 alike and placing them at opposite sides of the tank, return pipe 49 may be connected at either .side as may be more convenient in a given situation.

Top plate 15 carries a bore to which steam pipe 52 is connected. This opening in the top plate provides an outlet for steam from the tank located at a position above the normal water level in the tank so that water is not carried out by the steam. It is helpful to provide baffle 53 or some similar means to further eliminate any water entrained in the steam as it moves toward the steam outlet.

It is preferable to provide tank 14 with a safety valve 55 in order to limit the pressure which may be built up within the circulating system by escaping steam. The system is essentially a low pressure system so that the safety valve may be set to open at a low pressure, for example pounds over atmospheric. The safety valve may be of any suitable type and located at any convenient point, as for example by mounting it on cover Where it is in communication with the interior of tank 10 at a point above the water level in the tank.

Fig. 1 shows a typical cooling system for an internal combustion engine with a steam separator 14} of my improved design. The arrangement shown is siutable either for a mobile or a stationary installation. The hot water outlet for the block of engine 12 is connected through conduit means 56 to inlet section 18 of the separator. Outlet tube 46 of the separator is then connected by line 57 to the intake port of circulating pump 58, of any conventional type. Line 57 and pump 58, if any, may be considered to be conduit means connecting the liquid outlet of the separating means with the inlet to block 12. Pump 58 is driven in a well-known manner and delivers water to the engine block, forcing the water to circulate through the cooling passages and out through the hot water outlet. It will be noted that the primary water circulation in this case is from the block through the steam separator and then to the pump and back into the block. The separator is preferably located relatively close to the hot water outlet and near the top of the engine block in order to maintain the water level at the proper height within the separator.

Steam from the separator is taken by pipe 52 to a radiator or condenser 60 through which air is drawn by fan 61 in a conventional manner in order to cool the steam within the radiator and return it to the liquid state. Radiator 60 may have an air vent and vacuum breaker 62 of conventional design to limit pressure in the radiator to a low value, typically 10 pounds or less. Vent 62 and valve 55 provide adequate safety measures to relieve excessive pressures and isolate the system from the atmosphere so that the coolant circulates in a closed circuit or cycle. The condensate at the bottom of the radiator flows by gravity through pipe 49 back into the steam separator. Normally the highest point in the cooling system is the top of radiator 60 and the radiator is so located with respect to tank 14 to obtain gravity flow of water from the radiator back to the separator tank.

A second return line.64 connects the bottom of radiator 60 with line 57 at or close to the intake of pump 58.

Flow in this line is by gravity and controlled by valve 65. Return of condensate may be via eitherline 49 or linc fifi, or by both. Line 64 has the effect of reducing the temperature of water entering pump 58 morethan ifline 4 9 is used exclusively. In general, it is satisfactory .to re turn condensate to the circulating streamat any point in the circuit outside the block where there is relativelyiow pressure. The preferred range of positions for connecting the condensate return line is atorafter steam separation and before entering the pump. 1

Having described the construction of my improved vapor separator and engine cooling system, I will now describe briefly their operation. Under normal engine operating conditions, the cooling system contains a liquid, typically water, maintained at'or near the boiling temperature. As the water circulates through the engine block, heat is given up to the water and as long as the pressure on the water is above the vapor pressure for the existing temperature, no steam is formed except possibly for local formation of steam bubbles right at a heated surface. However suchsteam is quickly absorbed and cooledin the main stream of water. This is a localized condition which also occurs at times in conventional types of cooling systems. Since the water enters the block not far below the boiling temperature, the added heat supplies chieflythe heat of vaporization of the water rather than changes its temperature and it is for this reason that the water can absorb a large amount of heat energy from the engine without requiring any substantial rise in temperature.

Ordinarily, when the circulating water passes out of the cylinder head, the pressure on the fluid stream drops and, without the addition of any further heat, steam begins to form in the fluid stream because the vapor pressure is now higher than the pressure on the water. As a consequence, the stream of fluid passing through conduit 56 and entering the separator may contain some steam so that the fluid stream entering the separator may be already a mixture of the liquid and vapor phases of the coolant.

As this body of fluid passes through the initial converging passageway 20, the cross-sectional area of the stream is decreased and its velocity is proportionately increased with the result that it is moving at a considerable velocity as it leaves the initial section of the inlet passageway. Passing into the final section 22 of the inlet passageway, the cross-sectional area of the stream is suddenly increased, a change which is attended by a sudden decrease in pressure on the water. As a result, a substantial amount of the water is vaporized to steam. This conversion of water to steam takes place throughout the entire length of passageway 22 and the fluid stream discharged from the tubular inlet means into separating chamber 25 contains a high proportion of steam, considered from a volumetric standpoint.

By way of example, assume a brake horsepower Diesel engine operating at half load with water circulating in the cooling system at the rate of 50 gallons per minute. Steam may be assumed to be produced at the rate of 2.2 pounds per brake horsepower hour or a total of l 10 pounds per hour for a half load of 50 horsepower. Under these conditions the volume of the circulating water is .11]. cubic foot per second while the volume of steam at atmospheric pressure is .800 cubic foot per second, the total volume of the combined steam and water amounting to .911 cubic foot per second. Flow of this quantity of steam and water through a pipe having a two inch irternal diameter is at the rate of 39 feet per second.

The inlet means of the separator causes the fluid stream to undergo an abrupt decrease in pressure which allows a portion of the water to vaporize quickly as it travels through passageway 22 to ,form a moving body of fluid 7 which, by the time that it issues from the end of inlet passage 22, is largely steam and has a total volume several times that of the fluid stream leaving passage 20. The

increase in volume causes a corresponding increase in velocity of forward movement as the fluid stream moves through passage 22.

Inside separating chamber 25, the steam separates from the water, rises to the top of the chamber and leaves through steam port 26. Above the chamber and within well 28 there is a mixture of water and steam since the rising steam carries a certain amount of water with it which tends to fall back into separating chamber but the greater mass of water in tank 14 is kept away from steam vent 26 by walls 29 and 31 to facilitate separation of steam and water. The velocity imparted to the water at the time of entrance into separating chamber 25, carries the Water through the chamber and into the enlarged inlet end of nozzle in spite of the considerable turbulence in the chamber. In order to facilitate entry of water into the outlet, it is desirable that the inner end of passageway 42 be relatively large, as shown. The passage then narrows down, decreasing in cross-section in the direction of fluid flow, to keep the water moving at a relatively high velocity, for the water retains much of the velocity imparted to it by the expansion of steam in passage 22. The velocity head of the water is retained and used to feed it to the circulating pump, as mentioned below. The forward movement of the water through the separating cham ber draws into the chamber a certain amount of water from the tank through opening 35. This is in the nature of a jet action and serves to replenish the water which is carried out of the separating chamber by the steam.

Two things are accomplished by placing the steam separator between the hot water outlet from the engine block and the intake of circulating pump 58. In the first place, the total heat content of the circulating water has been reduced by the vaporization and subsequent separation of a portion of that stream of water. The remaining water is thus conducted via line 57 to the inlet of the pump in a condition in which the tendency of the water to form a steam pocket at the inlet side of the pump is eliminated, or at least very much reduced. In the second place, the water is moving at a relatively high velocity as it passes through and leaves the separator and therefore has sufiicient kinetic energy to carry it into the pump even though a slight vapor separation does form at the pump intake. As a result, the pump is always primed and continues to deliver cooling medium to the engine even though that medium is near the boiling temperature at the intake to the pump.

The vaporized fraction of the cooling medium goes through pipe 52 to radiator 60 where heat is rejected to the surrounding atmosphere, in a Well-known manner. The steam entering the radiator is at or above the boiling temperature. This is a substantially higher temperature than is usually present in a system designed to operate with the water circulating at a maximum temperature of say to F. As a result, there is always a much greater temperature differential between the temperature of the entering steam and the ambient air than there is in conventional lower temperature cooling systems. The greater temperature differential brings about a greater rate of heat exchange and permits radiator 60 to be made smaller and more inexpensively than is the case in conventional types of radiators where a large cooling surface is required. In some cases the radiator may be reduced by one-half, when my improved cooling system is installed, compared with conventional cooling systems.

When the steam is cooled, it liqui-fies and is returned either to tank 14, where it mixes with the water in the tank and is returned to circulation through opening 35, or through alternate line 64 direct to pump suction port. Return of the condensate from radiator 60 lowers the temperature of water moving back to the engine through pipe 57. If both lines 64 and 49 are used, a valve at 65 is used to regulate flow in the lines. In some cases a greater cooling at the pump inlet may be obtained by using only line 64.

The engine cooling system containing my novel form of vapor separator is designed to operate with the main from the main stream the amount of heat required to supply the heat of vaporization for that fraction of the stream converted into steam. This steam fraction is then separately cooled and returned to the circulating stream. As steam is formed and extracted from the water, the fluid stream consists of a mixture of steam and water that expands in volume and when confined within the passageways of the system the increase in volume brings about a corresponding increase in velocity. This velocity of the liquid remaining after removal of the steam fraction supplies the kinetic energy necessary to carry the water into the pump at all times even though there may be a tendency for a slight vapor separation at the inlet side of the pump. The result is a continuous feed to and delivery from the circulating pump. The kinetic energy imparted to this moving stream of water makes it unnecessary to apply any substantial static or gravity head to the system to maintain a pressure in excess of the vapor pressure and so insure a proper feed of liquid at all times to the pump intake.

Having shown and described a preferred form of my invention and indicated various possible modifications, it will be evident that various other changes may be made without departing from the spirit and scope of my invention. Consequently it is to be understood that the foregoing description is considered to be illustrative of, rather than limitative upon, the appended claims.

I claim:

1. In a liquid cooling system for an internal combustion engine, the combination comprising: an engine block having an inlet and outlet for liquid coolant; a tank for containing a body of liquid; a liquid inlet for the tank connected to'and receiving liquid from the engine block outlet, said inlet including passage forming means providing a liquid passage of gradually decreasing cross section followed by an abrupt increase in cross section at which pressure is reduced to form vapor; a vapor separating chamber within the tank and opening to the tank interior below the liquid level therein, said chamber receiv ing liquid from the inlet for the tank; a liquid outlet passage from the tank communicating with the separating chamber and discharging to the tank exterior; a vapor outlet from the tank above the liquid level therein; a pump delivering liquid to the engine block inlet and receiving liquid from the tank; and means for cooling and condensing vapor received from the tank.

2. A liquid cooling system as in claim 1 in which the inlet passage forming means of the tank, the steam separating chamber, and the outlet passage from the tank are aligned with each other to provide a substantially straight liquid path through the tank.

3. A liquid cooling system as in claim 1 in which the separating chamber has a vapor outlet port in its upper side below the liquid level and which also includes a shield surrounding the vapor outlet port, said shield extending from the separating chamber to a position above the liquid level of the tank.

4. A steam separator for use in an engine cooling system, comprising: a tank for containing a body ofwater leaving a space Within thetank above the water level; a liquid inlet for the tank positioned below the water level in the tank, said inlet including means forming a passage of which the cross section initially decreases in the direction of flow and then abruptly increases; a steamseparating chamber within the tank opening to the tank interior and receiving water and steam from the liquid inlet; a water outlet passage communicating with the separating chamber and discharging water therefrom to the tank exterior; and a steam outlet from the tank at a location above the water level.

5. A steam separator as in claim 4 in which the inlet, the steam separating chamber, and the water outlet are aligned with each other to provide a straight path through the tank.

6. A steam separator as in claim 4 in which the separating chamber has a steam outlet port in its upper side.

7. A steam separator as in claim 6 in which a shield surrounds the steam outlet port and extends to a height above the water level in the tank.

8. A steam separator as in claim 4 in which the inlet passage has a section of gradually increasing cross section between the position of abrupt increase and the end opening to the separating chamber.

9. A steam separator for use in an engine cooling system, comprising: a tank for containing a body of Water leaving a space above the water level; tubular means forming a water inlet passage at one side of the tank below the water level, said passageway having an initial section of gradually decreasing cross-section and a final section of gradually increasing cross-section, there being an abrupt increase in cross-section between the two sections; other tubular means providing an outlet passageway at the opposite side of the tank; a steam separating chamber in the tank communicating at opposite ends with said inlet and said outlet passageways and co-axial with both passageways, said chamber having a. steam port in its top wall lower than the water level and a water intake port; and a steam outlet from the tank above the water level.

10. A separator for separating vapor and liquid phases in a moving stream of fluid, comprising: a tank adapted to hold a body of liquid; a fluid inlet to the tank comprising means forming a passage which gradually decreases in cross-sectional area in the direction of a stream flow followed by an abrupt increase in cross-sectional area, the location of abrupt increase in area being spaced from the discharge end of the inlet passage; a vapor separating chamber receiving the stream of vapor and liquid from the inlet; a vapor outlet in the upper portion of the tank; and a fluid outlet from the tank comprising means forming a passage axially aligned with but spaced from the discharge end of the inlet passage.

11. A separator as in claim 10 in which the inlet passage increases gradually in cross-sectional area in the direction of stream flow between the location of the abrupt increase in area and the discharge end of the inlet passage.

12. A separator for separating vapor and liquid phases in a moving stream of fluid that is heated substantially to boiling, comprising: a tank adapted to hold a body of liquid; fluid inlet means for the tank, the inlet means comprising linearly extending passage forming means that confines and gradually reduces the cross-sectional area of the stream and then suddenly increases the crosssectional area of the stream to vaporize a portion of the heated liquid, while continuing to direct the entire stream of fluid; means defining a vapor separating zone in the tank receiving fluid from the inlet means; a vapor outlet from the tank; and liquid outlet means for the tank adjacent and receiving fluid from the separating zone; the inlet means, the separating zone, and the outlet means all being so arranged and constructed as to direct the liquid phase over an essentially straight line path through the separator.

References Cited in the file of this patent UNITED STATES PATENTS 1,311,528 Muir July 29, 1919 1,485,390 Gowing Mar. 4, 1924 1,630,068 Muir May 24, 1927 1,812,899 Pope, Jr. July 7, 1931 1,860,258 Lyon et a1. May 24, 1932 2,321,882 Wallace June 15, 1943 FOREIGN PATENTS 670,161 France Aug. 17, 1929 334,133 Italy Jan. 22, 1936 500,953 Great Britain Feb. 16, 1939 

